I was installing new cables on my Shimano Dura Ace 7900 system and I accidentally broke part of the "unit cover." In the pdf given at the link below it is part number 8 (Y-6SC98210). Supposedly it helps in removing the old cable to remove this cover first. It looked attached flimsily and with not much force I pulled it out, but that broke the plastic right where it attaches to the anchor bolt. I've called around but bike shops don't keep that sort of thing in stock. I can still put it there, I'm considering just taping it on with electrical tape, what do you think? Is that a bad idea? It seems the shifter should still work as it relies on having tension in the system apart from this cover.

http://bike.shimano.com/media/techdo...9830683887.pdf

Note that it's also mentioned in the installation instructions here:
http://bike.shimano.com/media/techdo...9830702962.pdf